Method of making electrically-conducting bodies for use as contacts.



'NITED STATES PATENT OFFICE.

HERMAN N VIERTEL, OF CHARLOTTENBURG, AND GEORG EGLY, OF LICHTENBERG, NEAR BERLIN, GERMANY, ASSIGNORS TO GEBRUDER SIEMENS & COMPAGNIE, OF (YHARLOTTENBURG, NEAR BERLIN, GER- MANY.

Specification of Letters Patent.

Patented Jan. 29, 1907.

.* n ioation and September 22.1906. seal N 885.832.

To all whom it may concern:

Be it known that we, HERMANN VIERTEL, engineer, of Charlottenburg, Berlin, Germany, and GEORG EoLY, chemist, of Lichtenberg, near Berlin, German have jointly invented a certain new am useful Im roved Method of Making Electrically-Con ucting Bodies for Use as Contacts, and do hereby declare that the following is a'full, clear, and

exact description of the same.

The present invention relates to a method. of manufacturing electrically conducting bodies for use as sliding and pressure'contacts, said bodies consisting of metallic alloys and carbon, consisting 1n the bodies being made by mixing metallic powders and carbon and subsequently pressing and molding in mixture and heating them in an indifferent or reducing atmosphere until softening and alloyage take place.

The manufacture of molded electricallyconducting bodies from mixtures of metal and carbon by mixing the mixtures with an agglutinant-for example, tar-and then pressing them, embedding the same in powdered carbon, and burning them, is in itself known. The cohesion of the particles of metal and carbon is effected in these bodies by means of the tar-coke, which remains behind after the vaporization of the tar; but such electrically-conducting bodies when employed as sliding or pressure contacts do not always meet the demands placed on them with respect to durability, hardness, and electrical conductivity. It has, moreover, been attempted to obtain greater conductivity and durability and the desired degree of hardness by copporeplatin the particles of carbon in the first place an then tin-plating them and molding the material thus prepared with so much trouble by means of pressure and under heat; but a sim- 1e and certain method is also not obtained 1n this manner. It is also not new to burn resistance bodies which consist of carbonaceous commixturcs in a reducing or in different atmosphere.

Now in accordance with the present invention the manufacture of electrically-conducting bodies which meet all the requirements placed on them, particularly when used as dynamo-brushes and the like, is effected in a simple manner and with constant perfect uniformity b the metals of which the concerned metal ic alloy consists being employed in powdered form. The different metallic powders-for example, copper and zinc or copper and tin or copper, zinc, and tinand the like other mixtures are mixed intimately with carbon Without preparation, molded, and heated to about 600 centigrade in an indifferent or preferably in a reducing atmospherefor example, in an hydro'genous atmosphere-whereby the se arate metallic powders become alloyed wit one another and form an exceedingly uniform mass with a metallic appearance with the inclosed carbonaceous material.

A mixture particularly suitable for dynamo-brushes consists, for example, of seventy-five parts of copper, twenty parts of tin, and five parts of zinc. This mixture of metals has added to it, according to the desired conductivity and hardness, more. or less graphitefor example, ten per cent. of graphiteand the mixture is thoroughly kneaded with water or other agglutinant, pressed in molds, and then heated in an hydrogenous atmosphere until softening and alloyage of the metallic powders take place. The conductivity of such bodies can be still more increased if they are subjected again to pressure after the metallic coalescence has taken place.

What we do claim as our invention, and desire to secure by Letters Patent, is-'- 1. A method of making electrically-conducting bodies for use as contacts consisting in intimately mixing together metallic powders and carbon, pressing and molding the mixture, and heating the same until softening and allo age take place.

2. A met 0d of making electrically-conducting bodies for use as contacts consisting in intimately mixing together metallic powders and carbon, adding thereto and mixing therewith an agglutinant, pressing and molding the mixture, and heating the same until softening and alloyage take place.

3. A method of making electrically-conducting bodies for use as contacts consisting in intimately mixing together metallic powders and carbon, adding thereto and mixing therewith an agglutinant, pressing and moldl ing and. alloyage take place, substantially as mg the mixture, and heating, the same in a herein described.-

' reducing atmosphere until softening and alloyage take place.

h 5 4. A method of making electrically-conducting bodies for use as contacts consisting in intimately mixi together copper, tin and zinc in the form 0 powder, adding thereto and mixing therewith water, pressing and r0 molding the mixture, and heatingthe same.

in an hydrogenous atmosphere until soften- In witness whereof we have hereunto set our names, this 7th day of September, 1906, I 5 1n presence of two subscribing witnesses.

HERMANN VIERTEL. GEORG EGLY.

, Witnesses:

HENRY HASPER, WOLDEMAR HAUPT. 

